Martin ParrFunerals

Most of the photographs people take with their cameraphones are of little value in terms of documentary. All you get is people smiling with each other or in front of tourist locations. They don't tell us much about what's going on in the real world.

The Mass Observation project had a very particular way of recording its subjects. The directives were designed to make people think, and to photograph things they wouldn't normally do. That's why I set the assignment to photograph a funeral. It's a very difficult assignment because of all the baggage and prejudice around it. You can easily take photographs at a wedding – no one would question it. But funerals are different.

I always take photographs when I attend a funeral. Most people there know who I am and expect me to be there with my camera. I think many of the photographs submitted for my directive come from family albums, rather than from people going out there specifically. That's understandable: it's a hard task. I think the most successful image is of the family burying an urn, with a bunch of balloons. But the assignment shows that some people do have common sense, and have taken photos at funerals because they are an event worth remembering. The camera's job is to document life, and it's crazy not to do it.

Sometimes you feel uncomfortable taking a photograph, but that's all part of the job. Most photos are propaganda – whether they're in a family album, or advertising, or even in a newspaper like the Guardian, beyond the role of hard news stories. Think about travel images used to sell holidays, recipes to endorse supermarket ads. Documentary photography's role is to challenge our daily dose of photo propaganda.

Cornelia ParkerSmoking

When the smoking ban was introduced in 2007, everyone at work had to go out on the streets to smoke, and you began to see these curious little social groups appearing. I used to live near the City of London, where you'd see lines of people standing outside offices exhaling, sometimes on their own or, a bit like dog owners, talking to fellow smokers whom they barely knew. I kept meaning to record the phenomena. Now those groups have changed. People are all checking their mobiles; it's more individualistic, less self-conscious. In a few years' time, the social aspect to smoking might disappear altogether, as people wean themselves off or it becomes progressively more stigmatised. Meanwhile, in Africa and China the numbers of new smokers are multiplying fast.

Photography has become increasingly important in our lives. Most people have a camera on them now, in the form of their phone. Almost everything is recorded. I take images all the time on my iPhone, using it as a sketchbook. I have a few photo-dialogues going on with friends; it's a way of communicating without words. It seems absolutely normal for people to stand out in the street taking photographs and for everyone to just ignore it and carry on with their lives. Back when the Mass Observation directives started, being photographed was much more of a novelty.

I like that Mass Observation recorded things that might seem mundane – the style of clothing and cars, little mores of society you wouldn't normally think of capturing. Martin Parr's directive about funerals is a great example of an under-recorded subject: I've been to a few funerals, but never took a photo; it just seemed taboo.

When I took my photos of smokers, I did ask some people's permission; others, I just took a quick snap. Invasion of privacy might just be part of the project. People might feel uncomfortable about being publicly branded a smoker; now that they've been forced on to the streets, it's difficult to be coy. Most people, even non-smokers like myself, have had a puff. Inhaling and exhaling: it's a part of our death drive.

Last week photographer Martin Parr asked you to share images taken of, or at, a funeral. His assignment was part of the This Is Your Photo project in collaboration with the Photographers' Gallery in London